In contrast to PCR, isothermal amplification enables rapid and specific amplification of DNA at constant temperature (60-65 °C) avoiding the requirement of thermal cycling. An optimized Bst polymerase with high strand displacement activity generates an amplification factor of up to 109 which is comparable to 30 cycles in a PCR assay. This allows the detection of a target gene within 10-30 minutes.
Phi29 DNA polymerase is the enzyme of choice for whole genome amplification (WGA).
Isothermal amplification has been observed to be more resistant to inhibitors in complex samples (e.g. blood, plant tissue) compared with PCR due to the use of Bst polymerase instead of Taq. This allows the rapid detection of a target gene from minimally processed samples and makes it the method of choice for a fast screening of individual DNA samples.
Limitations may occur if precise target quantifications are requested or if amplification of several genes in a single tube (multiplexing) is essential.